Yamaha 2009 YZF-R1 (Y) Service Manual page 278

Valve seat width
Valve seat width (intake)
0.90–1.10 mm (0.0354–0.0433
in)
Limit
1.60 mm (0.06 in)
Valve seat width (exhaust)
1.10–1.30 mm (0.0433–0.0512
in)
Limit
1.80 mm (0.07 in)
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a. Apply Mechanic's blueing dye (Dykem) "b"
onto the valve face.
b. Install the valve into the cylinder head.
c. Press the valve through the valve guide
and onto the valve seat to make a clear
impression.
d. Measure the valve seat width.
TIP
Where the valve seat and valve face contacted
one another, the blueing will have been
removed.
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4. Lap:
• Valve face
• Valve seat
VALVES AND VALVE SPRINGS
TIP
After replacing the cylinder head or replacing
the valves and valve guides, the valve seat and
valve face should be lapped.
ECA14B1031
This model uses titanium intake valves.
Titanium valves that have been used to lap
the valve seats must not be used. Always
replace lapped valves with new valves.
TIP
• When replacing the intake valves, replace
the intake valves without lapping the valve
seats and valve faces.
• When replacing the cylinder head or intake
valve guides, use new valves to lap the valve
seats, and then replace them with new intake
valves.
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a. Apply a coarse lapping compound "a" to
the valve face.
ECA13790
Do not let the lapping compound enter the
gap between the valve stem and the valve
guide.
b. Apply molybdenum disulfide oil onto the
valve stem.
c. Install the valve into the cylinder head.
d. Turn the valve until the valve face and valve
seat are evenly polished, then clean off all
of the lapping compound.
TIP
For the best lapping results, lightly tap the
valve seat while rotating the valve back and
forth between your hands.
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